<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2014-03-03</periodOfReport>

    <issuer>
        <issuerCik>0001472787</issuerCik>
        <issuerName>First American Financial Corp</issuerName>
        <issuerTradingSymbol>FAF</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001507625</rptOwnerCik>
            <rptOwnerName>Seaton Mark Edward</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1 FIRST AMERICAN WAY</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SANTA ANA</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92707</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>EVP &amp; Chief Financial Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2014-03-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>935</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>26.14</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>48174</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2014-03-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1628</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>26.57</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>46546</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                    <footnoteId id="F6"/>
                    <footnoteId id="F7"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Payment of tax liability by withholding securities incident to the vesting of restricted stock units.</footnote>
        <footnote id="F2">Includes 189 unvested restricted stock units (&quot;RSUs&quot;) acquired in a pro rata distribution by The First American Corporation (&quot;FAC&quot;) on account of an original grant of 381 FAC RSUs, of which 305 were unvested at the time of the distribution and shares acquired through automatic dividend reinvestment.  The vesting schedule of the FAC RSUs, vesting in five equal annual increments commencing 03/20/10, the first anniversary of the grant, has been carried over to the issuer RSUs.</footnote>
        <footnote id="F3">Includes 282 unvested RSUs acquired in a pro rata distribution by FAC on account of an original grant of 287 FAC RSUs, all of which were unvested at the time of the distribution and shares acquired through automatic dividend reinvestment.  The vesting schedule of the FAC RSUs, vesting in five equal annual increments commencing 03/22/11, the first anniversary of the grant, has been carried over to the issuer RSUs.</footnote>
        <footnote id="F4">Includes 843 unvested RSUs acquired pursuant to an original grant of 3,130 RSUs and shares acquired through automatic dividend reinvestment, vesting in four equal annual increments commencing 3/3/12, the first anniversary of the grant.</footnote>
        <footnote id="F5">Includes 3,374 unvested RSUs acquired pursuant to an original grant of 6,477 RSUs and shares acquired through automatic dividend reinvestment, vesting in four equal annual increments commencing 3/1/13, the first anniversary of the grant made on 2/29/12.</footnote>
        <footnote id="F6">Includes 13,010 unvested RSUs acquired pursuant to an original grant of 17,002 RSUs and shares acquired through automatic dividend reinvestment, vesting in four equal annual increments commencing 3/4/14, the first anniversary of the grant.</footnote>
        <footnote id="F7">Includes 20,005 unvested RSUs acquired pursuant to a grant vesting in four equal annual increments commencing 2/27/15, the first anniversary of the grant.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Greg L. Smith, Attorney-in-Fact for Mark E. Seaton</signatureName>
        <signatureDate>2014-03-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
